The invention relates to pouch packs for fibrous material, especially cut tobacco, consisting of a preferably multi-layer blank made of plastic foils, which forms a pocket with a front wall, a rear wall, a bottom and side walls and, as a continuation of the rear wall, a covering tab, an orifice of the pocket being sealed by a closing seam (weld or sealed seam). The invention also relates to a process for making a pouch pack of this type and to an apparatus.
Pouch packs for tobacco are known in various embodiments. The type of pack of this kind with which the invention is primarily concerned is referred to as a side-folding or lateral fold pouch. A characteristic of this is the design of the pocket for receiving the tobacco with a bottom and with side walls which, when the pouch is full, are directed perpendicularly to the front wall and the side wall. In pouch packs of this type, the rear wall of the pocket is extended and forms a covering tab which, when the pouch pack is closed, is folded over against the front wall of the pocket.
To improve the capacity for keeping the tobacco fresh (preservation of the aroma and moisture) over a prolonged period up to the time of use, pouch packs having a pocket orifice which is closed after filling are known. The closure is supposed to be easy to eliminate. Especially suitable for this purpose are tear-open sealed seams which are made by the heat-sealing of an applied strip of material (the so-called peel-seal seam).
The packs are made from a blank which originally has a rectangular shape. A particularly widespread embodiment of the pack consists, here, of 2 plastic foils connected to one another all-round on the side edges and of a paper insert located between these. This embodiment is disclosed in published U.K. patent application No. 2,061,713. The latter extends over the full dimensions of the blank with the exception of edge seams which are required. This necessarily presents folding difficulties at the transition from the pocket made with side walls into the covering tab made of equal width. If, for example, the (filled) pocket is erected into an approximately cuboid shape, there arise lateral strip-shaped projecting lengths in the region of the covering tab, specifically in a width of half the width of the side wall (side-wall half). This lateral projecting length of the covering tab is conventionally folded over inwards so that the covering tab essentially has the same width or transverse dimension as the pocket (or the front wall of the latter). In the known pouch packs designed as lateral fold or side-folding pouches, the transition from the pocket into the covering tab is achieved by folding the side walls of the pocket inwards in the form of a V in the region of the pocket orifice. Consequently, the side-wall halves form a V-shaped channel is this region. Its legs are continued, in the region of the covering tab and, if appropriate, in the region of a (shorter) gripping tab, as a strip-shaped projecting length folded over inwards. As a result, the finished full pouch pack is essentially cuboid without projecting lengths or side strips caused by the covering or gripping tabs.
However, the above-mentioned solution is disadvantageous as regards the appropriate application of a closing or sealing seam in the region of the orifice. Irrespective of whether this is made, after filling, by thermal welding of the plastic foils or by activating strips of material previously applied, in either case the closing seam in the lateral regions of the pocket or the orifice is unsatisfactory because of the accumulation of material arising there as a result of the V-shaped folds. Leaky regions are obtained here. The paper insert has 4 layers here, with plastic foils located between each one. Outside the region of the V-shaped folds, only 2 layers of paper need be allowed for in welding.